Cross-coupled inverters 9, 11 have been used in pseudo-differential inverter strings to generate a differential set of transitions in otherwise uncoupled single-ended complementary metal-oxide-semiconductor (CMOS) signal paths, such as that shown in FIG. 1. The circuit arrangement 3 of the cross-coupled inverters 9, 11 insures that a time skew in either the top or bottom differential pair of signals is not allowed to propagate. The cross-coupled inverters 9, 11 are used to de-skew differential local oscillator (LO) clock waveforms prior to mixers 8, 10 for 50% duty cycle LO waveforms. Inverters 5 & 7 are inverter buffers in the forward path of the circuit arrangement 3.
The circuit arrangement 3 of the cross-coupled inverters 9, 11 de-skews input waveforms 12 at outputs 4, 6 by cross-coupled inverters 9, 11. The de-skewed waveforms are shown in FIG. 2. As demonstration, the waveforms 12, 14 are pseudo-differential CMOS input swings that have been deliberately skewed from perfect differential by 5 degrees at 1.6 GHz. The forward path and cross-coupled inverters “negotiate” on when to actually allow the output transitions to occur and the result is that the crossing voltage of waveforms 16, 18 are much closer in agreement than were the skewed input crossing voltages.
In addition, rediscovery of the N-path filtering technique has highlighted the emerging need for a technique to improve the pseudo-differential balance and duty cycle of 4-phase non-overlapping clocks.
Desirable in the art is an improved system and method for generating non-overlapping waveforms that would improve upon the conventional frequency conversion mixers.